新しいパラメータを用いた道路橋の疲労信頼性評価

抄録

Recently there have been many reports on the stress measurement of highway bridges. However, a generalized method is not still provided on how to introduce the results of stress measurement into the fatigue reliability assessment. In this paper, two new parameters, called “fatigue resistance c” and “fatigue-damage-accumulation q”, are proposed to make it easy to introduce the results of stress measurement of a monitored bridge into the fatigue reliability assessment of highway bridges. Using a fatigue test database, the probability distribution of c is determined for various structural details. It is shown that for fatigue failure, the assumption of q=c is equivalent to the Miner's linear damage rule. The characteristics of the fatigue-damage-accumulation q of highway bridges are discussed. The application of the advanced first-order second-moment method to the state function of g=c-q gives the fatigue reliability assessment of highway bridges. It is expressed in terms of the design equivalent stress range and the allowable fatigue stress range with partial safety factors. The relation between the safety index and the lapse of time from opening to traffic is formulated. The safety index is shown to decrease with the time in logarithm scale.